Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 350 PM EDT Sun Jun 23 2019 Valid 12Z Thu Jun 27 2019 - 12Z Mon Jul 01 2019 Models are starting to hint at a pattern change across Alaska by next weekend with a potential breakdown of the upper ridge, opening mainland Alaska up to stronger and more active westerly mid/upper-level flow. Before that occurs, models show improved agreement during the early part of the extended period on a weakening frontal system crossing the eastern Aleutians. The majority of upper-level energy associated with this system should be deflected either north toward eastern Russia or south into the northern Pacific due to the upper ridge anchored over western mainland Alaska at that time. A blend of the ECMWF and GFS served as a starting point for the forecast on day 4 (Thu) with a 50/50 deterministic/ensemble blend on day 5 (Fri). After that, spread increases quite a bit with the GFS ejecting another shortwave east across the Bering Sea, and breaking down the upper ridge much more quickly than the ECMWF/CMC. At this time a trend toward ensemble means was preferred during days 6-8 (Sat-Mon), which does break down the ridge at least a day slower than the GFS. This solution should allow shortwave energy and an associated surface frontal system to reach mainland Alaska on Sun, pushing inland by Mon as it weakens. This setup would bring an end to the drier conditions seen across much of Alaska recently, with an increase in moisture/showers especially for southern mainland Alaska. Ryan Additional 3-7 Day Hazard information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html